[pure-silver] Re: LED enlarger light source
- From: Snoopy <snoopy@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 05 Feb 2009 16:19:22 +0100
Hia,
I tried to replace the halogen lamp of my Durst with a "halogen lamp2
made up of several stron white LEDs. I did this because I wanted to
avoid the "afterglow" of the incandescent bulbs.
I was unhappy with the results.
Fiurstly they were simply not as brigt, despite the fact that I tried
ben ones that plug directly into the mains suplly.
Secondly the cause "knobbly" lighting, becase thaey wee made up of 12
LEDs bunched together. So the illumination was very uneven to put it
mildly, actually you might say it kinda sucked...
Love,
Snoopy
Chris Ellinger wrote:
>
>
> Don Sweet wrote:
>
>> High intensity LEDs covering the bluer parts of the specturm have been on
>> the market for the last 10 years or more. I wonder why they cannot
>> provide
>> an easy substitute for enlarger lamps; they are apparently stable,
>> with very
>> low power consumption and virtually heat generation, and last for
>> ages. A
>> switchable bank of mixed frequency LEDs would seem to be a natural
>> match for
>> VC paper. Has his been done, or do LEDs present some fiendish design
>> problem in this context?
>
>
> My experience is that the available high intensity blue LEDs have a
> relatively wide spectral bandwidth and won't produce "grade 5"
> contrast. This seems to be born out by Huws claim of grade 4.5 maximum
> contrast.
>
> Chris Ellinger
> Ann Arbor, MI
> USA
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